1. Field of the Invention
The present invention relates to method and apparatus for transporting underwater cut pellets and, in particular, to method and apparatus in which underwater cut pellets of synthetic resin, which have been formed by extruding the synthetic resin into the water through a die from a kneading and extruding machine or the like and then by cutting the same in the water, are carried by the water, and are then dehydrated and dried.
2. Related art
Conventionally, as underwater cut pellet transport apparatus, generally, there is employed underwater cut pellet transport apparatus which is structured in such a manner as shown in FIG. 2.
As shown in FIG. 2, synthetic resin material, which is supplied to a kneading and extruding machine 2 through a hopper 2a or the like, is melted and kneaded by a screw 2b which can be rotated by an extruding machine drive motor 1, is extruded in a strand form into the water through a granulating extrusion die 3 disposed in the leading end of the kneading and extruding machine 2, and is cut into pellets by an underwater cutting knife 4a which can be rotated on the surface of the extrusion die 3 by an underwater cutting knife drive motor 5 provided in an underwater cutting device 4.
The underwater cut pellets are cooled by the water that is fed from a cooling water tank 7 to the underwater cutting device 4 with a head pressure of 3-5 kg/cm.sup.2 by a cooling water circulating pump 6, and are then delivered to a cooling water dehydrating device 10 through a cooling water circulating pipe 8 having a cooling water switching three-way valve 9. In the cooling water dehydrating device 10, the water and pellets are separated from each other, the pellets are next carried to a drying device 11 where the water attached to the pellets is removed from the pellets, and the pellets are then delivered to a transport hopper 16 through a classifier 12. By the way, an exhaust fan 20 is connected to the upper portion of the drying device 11 or the like.
The pellets delivered to the transport hopper 16 are then fed to a plurality of pellet silos through an air feed pipe 19 having a silo switching valve 14 due to the head pressure of an air feed blower 17 having an air filter 18.
By the way, the pellets stored within the pellet silos 15 are discharged from the lower portions of the pellet silos 15, are put into bags, and are then shipped as products.
The water separated from the pellets in the cooling water dehydrating device 10, the attached water removed from the pellets by the drying device 11, and the water diverged by switching the cooling water switching three-way valve 9 are respectively collected into the cooling water tank 7 and, after then, as described above, the thus collected water is fed to the underwater cutting device 4 by the cooling water circulating pump 6, thereby carrying out a continuous automatic water circulatory operation.
Since the conventional underwater cut pellet transport apparatus is structured in the above-mentioned manner, there have been found in the same apparatus several problems as follows: That is,
(a) Because the conventional underwater cut pellet transport apparatus is composed of many devices, the apparatus itself is complicated in structure, which causes an increase in the cost of construction of such plant, that is, underwater cut pellet transport apparatus.
(b) While the conventional underwater cut pellet transport apparatus is divided into a pellet water cooling and drying line and a pneumatic feeding line in which dry pellets are fed to pellet silos by means of air pressure, these lines produce large noises which have ill effects on an operation environment.
(c) The pellets are rubbed against the inner wall of the pipe of the pneumatic feeding line to thereby produce film-like resin shavings, while the resin shavings are mixed into the product pellets.